LONG-TERM SOLUBLE INTERLEUKIN-2 RECEPTOR LEVEL OF HEART-TRANSPLANT RECIPIENTS

We studied the plasma soluble interleukin 2 receptor (SIL-2R) levels o f 16 heart transplant recipients without infections and 3 recipients w ith infections for a minimum of 6 months post-transplantation (PoTx) t o establish their long-term SIL-2R profiles and to investigate the rel ationships between SIL-2R levels and rejection, infection, and immunos uppressive therapy. Heart transplant recipients without infections cou ld be placed into three groups based upon their SIL-2R profiles. Four recipients had no episodes of rejection and reached a peak SIL-2R leve l within 1 to 2 months PoTx followed by a trough level over the next 4 months. The second group, with 8 recipients, had rejection episodes a fter reaching the peak SIL-2R level within the first 2 months, but the levels became variable before reaching a stable trough level. The thi rd group, with 4 recipients, experienced early rejection within 2 mont hs of transplantation, showed rather variable SIL-2R levels, and none had a characteristic peak. Rejection episodes, especially mild ones, d id not correlate with SIL-2R levels. Elevated SIL-2R levels were assoc iated with opportunistic infections; however, this alteration was not specific enough to distinguish infection from rejection. In addition, response to immunosuppressive therapy could not be reliably predicted by changes in SIL-2R levels. We conclude that SIL-2R levels can neithe r be used as an indicator of myocardial rejection or infection nor as a guide for immunosuppressive therapy in cardiac transplant patients.